Nefastus message was warning you that she would ease off the teasing if you choose to scare her...So, no teasing = sex after the concert ? I definitely never did that, because there's some kind of threatening message from the Dev, I can't remember for sure... With the new version I will definitely try it, thank you all very much for your recommendations !
But later on, if you invite lewdly her at the diner, she will tell you that you're sending mix messages...and drops her phone.
Pick it up for her and enjoy the view